Process of smelting ores



(No Model.)

.E. B. LUNGWITZ.

PROCESS OF SMELTING GRE S. No. 538,785 Patented May 7, 1895.

UNITED STATES PATENT OFFICE.

EMIL E. LUNGVVITZ, OF PUEBLO, COLORADO.

PROCESS OF SMELTING ORES.

SPECIFICATION forming part of Letters Patent No. 538,785, dated May 7,1895. Application filed December 3, 1892. serial No. 453.993. (Nspecimens.)

T0 all wk 01% it may concern.-

Be it known that I, EMIL E. LUNGWITZ, a subject of the Emperor ofGermany, residing at Pueblo, in the county of Pueblo and State ofColorado, have invented certain new and useful Improvements in Processesof and Apparatus for Smelting and Roasting Ores; and Ido hereby declarethe following to be a full, clear, and exact description of theinvention, such as will enable others skilled in the art to which itappertains to make and use the same.

The present invention relates to an improved process of smelting ores,and it has for its object to prevent the loss of metals byvolatilization.

It is well known that the boiling point of a substance depends uponthe-pressure exerted upon the liquid,'the boiling point rising with thepressure according to a law governed by. the nature of the substance.Sufficient pressure will prevent ebullition of a liquid, even if itstemperature be raised considerably beyond its boiling point underordinary pressure. To prevent volatilizationof the regulus onceformed,'it is only necessary to maintain a sufficiently high pressure inthe furnace. In the case of an ore containing lead and zinc oxides, forinstance, the zinc would volatilize at the temperature of the furnace,say 1,200 centigrade, if a sufficient pressure Were not exerted to raiseits boiling point to this temperature. From the researches of Dr. CarlBarus (Bulletin United States Geological Survey, No. 54, 1889, andconfirmed by my own investigation),we may conclude that the tension ofzinc vapor at this temperature would be about fifty pounds.

In the accompanying drawing is shown a central vertical section ofa'blast-furnace, illustrating one means for carrying my invention intoeffect. v

A represents the steel or similar casing of the stack, supporting andinclosing the firebrick B. The throat of the furnace is closed by a capor plate 0 having an opening controlled by a'trap-door G hinged to theunder side of the cap. This opening is preferably centrally located, butmay be placed toward the side of the throat if desired. The usual 1hopper D for feeding ore and fuel is inserted in the throat of thefurnace. The discharge opening in this hopper iscontrolled by atrapdoorD hinged to the under side of the hopper. The trap-doors C and Dmay, if desired, be replaced by ordinary bell closures' Tuyeres E of theusual construction supply the blast for raising the temperature, andalso for raising the pressure within the furnace so that the reducedmetal or oxides will not boil under the temperature necessary forconducting the process.

F is a second steel or other casing surrou nding the casing A. The spacebetween these two casings forms a water-and air-tight chamber in whichwater is kept circulating to cool the casing 'A; and to prevent injuryto said casing, if it should become exposed to the pressure withinthe-furnace through fusing of the fire-brick at any point, the water insaid chamber is kept under pressure equal to the pressure within thefurnace. Water is supplied to this cooling chamber, through the nozzlesg of the pipes G, leading from the bustle pipe G by any suitable pump,the water entering preferably near the throat of the furnace anddescending to the hearth, thus cooling the upper portion of the stackfirst, and being heated gradually as it approaches the hearth, where itescapes through a suitable discharge pipe G. This hot water may beutilized by feeding it directly to the boiler connected with the enginesupplying the blast for the furnace. Suitable pressuregages H and H areapplied to the furnace, to indicate the pressures exerted within thefurnace-and the cooling chamber respectively, in order that saidpressures may be kept equal.

Safety-valves I and I may also be applied to the furnace and the coolingchamber respectively to balance the pressures by removing any excess ineither. The furnace safetyvalve 1 is preferably located just below thetrap-door D',.and'through it the waste gases are discharged. Theconstruction of this valve is similar to that of a boiler safetyvalve.

The operation of my invention is as follows: A charge of fuel and ore isintroduced into the furnace through the openings in the plate 0 andhopper D, after which the trapdoors 0 and Dare closed. After the firesare started the blast is turned on through the tuyeres E until thepressure within the furnace exceeds the pressure at which the metal tobe reduced would boil under the temperature to be created by the blast.As soon as the ore is smelted the reduced metal sinks to the hearth,where it collects and may be drawn off through the tap-hole.Volatilization of the metal or regulus and of the oxides is thusprevented, as the pressure exerted upon the charge is so high that itcannot boil, and hence cannot volatilize and be carried off through thefurnace throat, or over into the fine-dust chamber. This is a feature ofgreat importance, as the metal once reduced sinks to the hearth, and isnot carried off by the flue to be returned through the hopper in theform of an oxide and resmelted. Besides, by the expansion of the blastin furnaces as at present constructed, the finer particles of the chargeare carried over into the flue-dust chamber, as the blast maintains itspressure only at the tuyeres, as any desired pressure is maintainedconstant throughout the furnace in my invention. However, the formationof flue-dust is almost entirely prevented.

The construction of furnace I have illustrated is especially designedfor continuous smelting and roasting without lowering the pressurewithin the furnace. When it becomes necessary to re-charge the furnacethe trap-door G (or hell, as the case may be) is opened, and fuel or orefed into the hopper, the trap-door D (or bell) being kept closed. When asufficient quantity of the charge has thus been introduced into thehopper the door 0 is closed and D is opened, when the fuel or ore entersthe furnace, the door D being closed after all the charge has been fedto the furnace by the hopper. It will be seen that while thus rechargingthe furnace none of its gaseous contents can escape, and the pressureremains undisturbed, as one of the exits is always closed and theinclosed gases cannot get beyond the cap or plate (J of the stack.

stares My process is applicable not only to the smelting and roasting ofores containing a single metallic element, but to ores containingseveral such elements. The pressure of the blast would of course dependupon the metal or metals to be reduced and to be oxidized from the ore,and where several metals are reduced and roasted simultaneously withinthe furnace the pressure would be suiticiently high to preventvolatilization of the metal to be tapped.

I do not wish to be understood as limiting myself to any specific meansfor regulating and balancing the pressures in the furnace and coolingchamber respectively, as the means so employed may be modified withoutdeparting from the spirit of the invention.

No claim is herein made to the process of roasting ores as the sameforms the subject matter of an application filed by me June 15, 1893,Serial No. 477,714. Neither is claim made to the form of furnace orapparatus herein illustrated, as the sameforms the subject matter ofanother application filed .by me as a division hereof October 1, 1894,Serial No. 524,553.

Having thus described my invention, what I claim, and desire to secureby Letters Patent, is-

The process of reducing ores containing as a constituent a volatilizablemetallic element which consists in smelting the ore and maintainingwithin the furnace a pressure higher than the pressure at which theresulting metal or regulus or one of its constituents would boil at thetemperature obtaining in the furnace, substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

EMIL E. LUNGVVITZ.

Witnesses:

THEO. LUNGWITZ, E. L. I-IEUsNER.

